Investigation the connection between the intermediate gamma-ray bursts and X-ray flashes

Gamma-ray bursts can be divided into three groups: short-, intermediate and long-duration bursts. While the progenitors of the short and long ones are relatively known, the progenitor objects of the intermediate-duration bursts are generally unknown, however, recent statistical studies suggest, that they should be related to the long-duration bursts. In this work we investigate whether there is a differ- ence between the global parameters of the X-ray flashes and intermediate-duration group of gamma-ray bursts. The statistical tests do not show any significant discrepancy regarding most of the parameters, except the BAT photon index, which is only a consequence of the defintion of the X-ray flashes.Comment: 9 pages, 10 figures, submitted to Astronomische Nachrichte

Direction Dependent Background Fitting for the Fermi GBM Data

We present a method for determining the background of Fermi GBM GRBs using the satellite positional information and a physical model. Since the polynomial fitting method typically used for GRBs is generally only indicative of the background over relatively short timescales, this method is particularly useful in the cases of long GRBs or those which have Autonomous Repoint Request (ARR) and a background with much variability on short timescales. We give a Direction Dependent Background Fitting (DDBF) method for separating the motion effects from the real data and calculate the duration (T90 and T50, as well as confidence intervals) of the nine example bursts, from which two resulted an ARR. We also summarize the features of our method and compare it qualitatively with the official GBM Catalogue. Our background filtering method uses a model based on the physical information of the satellite position. Therefore, it has many advantages compared to previous methods. It can fit long background intervals, remove all the features caused by the rocking behaviour of the satellite, and search for long emissions or not-triggered events. Furthermore, many part of the fitting have now been automatised, and the method have been shown to work for both Sky Survey mode and ARR mode data. Future work will provide a burst catalogue with DDBF.Comment: 16 pages, 28 figure

Dependence of the optical brightness on the gamma and X-ray properties of GRBs

The Swift satellite made a real break through with measuring simultaneously the gamma X-ray and optical data of GRBs, effectively. Although, the satellite measures the gamma, X-ray and optical properties almost in the same time a significant fractions of GRBs remain undetected in the optical domain. In a large number of cases only an upper bound is obtained. Survival analysis is a tool for studying samples where a part of the cases has only an upper (lower) limit. The obtained survival function may depend on some other variables. The Cox regression is a way to study these dependencies. We studied the dependence of the optical brightness (obtained by the UVOT) on the gamma and X-ray properties, measured by the BAT and XRT on board of the Swift satellite. We showed that the gamma peak flux has the greatest impact on the afterglow's optical brightness while the gamma photon index and the X-ray flux do not. This effect probably originates in the energetics of the jet launched from the central engine of the GRB which triggers the afterglow.Comment: 2012 Fermi Symposium proceedings - eConf C12102

O Nobel de Literatura do húngaro Imre Kertész – contextualização histórica

Aqui no Brasil, infelizmente a Hungria é muito pouco conhecida, então oque eu conto sobre o meu país freqüentemente é novidade para todos. Por isso fiquei contente quando o José Cotta me pediu para apresentar a Hungria e passar algumas informações sobre a minha pátria. Lembro do dia em que fiquei orgulhosa e feliz, pois, estando na casa de meus pais, abri o jornal e lá estava escrito que um escritor húngaro havia ganho o prêmio Nobel de Literatura. Mas ao mesmo tempo fiquei triste, pois não conhecia o Imre Kertész. Até então nunca tinha ouvido falar o seu nome. E não só eu me senti frustrada, mas também os grandes intelectuais, os políticos e os professores, que tentaram justificar como era possível que na própria Hungria Kertész fosse pouco conhecido. Tanto assim que a indicação dele para o Nobel não havia partido da Hungria, mas da Alemanha

Statistical analysis of the prompt and afterglow emission of the three groups of gamma-ray bursts

We investigated the main prompt and afterglow emission parameters of gamma-ray bursts detected by the Burst Alert Telescope (BAT) and X-Ray Telescope installed on the Swift satellite. Our aim was to look for differences or connections between the different types of gamma-ray bursts, so we compared the BAT fluences, 1-sec peak photon fluxes, photon indices, XRT early fluxes, initial temporal decay and spectral indices. We found that there might be a connection between the XRT initial decay index and XRT early flux/BAT photon index. Using statistical tools we also determined that beside the duration and hardness ratios, the means of the \gamma- and X-ray--fluences and the \gamma-ray photon index differ significantly between the three types of bursts.Comment: 7th Huntsville Gamma-Ray Burst Symposium, GRB 2013: paper 27 in eConf Proceedings C130414

Morphological evaluation of experimental autologous rectus fascia sheath vascular grafts used for arterial replacement in a dog model

Although experimental autologous patch or tubular conduit vascular grafts made from the internal rectus fascia sheath (IRFS) have been reported in the literature, thorough morphological evaluation and verification of the histological arterialisation of such grafts are lacking. Four purpose-bred Beagle dogs were utilised to create eight arterial internal rectus fascia sheath (ARFS) grafts implanted between bisected ends of the external iliac arteries. Four out of the eight ARFS grafts were patent after three months. Haematoxylin-eosin and Azan staining verified that the grafts gained a vessel-like layered structure with the presence of large amounts of collagen fibres. Although the inner surface of the intact IRFS was originally covered with claudin-5-negative and pancytokeratin-positive mesothelial cells in control samples, the internal cells of the ARFS grafts became claudin-5 positive and pancytokeratin negative like in intact arteries. Spindle-shaped cells of the wall of ARFS grafts were α-smooth muscle actin (α-SMA) positive just like the smooth muscle cells of intact arteries, but α-SMA immunoreactivity was negative in the intact IRFS. According to these findings, the fibroblast cells of the ARFS graft have changed into myofibroblast cells. The study has proved that ARFS grafts may be used as an alternative in arterial replacement, since the graft becomes morphologically and functionally similar to the host vessel via arterialisation